The purpose of this study was to evaluate the association between an abnormal aortic isthmus blood flow index and postnatal neurodevelopmental outcome in fetuses with placental circulatory insufficiency.
The purpose of this study was to evaluate whether changes of uterine arteries and aortic isthmus Doppler blood flow recordings could enhance the prediction of necrotizing enterocolitis.
Basically, two major causes, not mutually exclusive, must be involved to explain these findings: (a) a pronounced founder effect at the beginning of South America's colonization via the Panama Isthmus and/or (b) continuous gene flow between North American and Asian populations via the Circum-Arctic route after the Beringian collapse (see below).
None of the comparisons among genetic groups indicate contemporary gene flow, suggesting that the Isthmus of Tehuantepec is preventing gene flow between populations on either side of the isthmus, and that the more recently divergent populations from the Tuxtlas region and SMO also have interrupted gene flow.
A good result of the cardiosurgery was defined as systolic pressure gradient between the right superior and inferior limbs below 20 mmHg measured with a sphygmomanometer and the normal profile of the flow at the aortic isthmus assessed by conventional Doppler imaging.
The developmental score was analyzed in relation to the flow patterns in the fetal aortic isthmus, which were classified as follows: group A, net isthmic flow antegrade (defined as the ratio of the systolic antegrade to the diastolic retrograde velocity integrals) (n = 39); group B, net isthmic flow retrograde (n = 5).
Moreover, our results indicate that the Isthmus also represents a strong barrier to pollen flow in each species.
Also, the closure of the Central American Isthmus (Pliocene-3Ma) could have weakened the western flow of the Equatorial Countercurrent [ 45, 59].
Results: Nonoptimal neurodevelopment was observed in 19 (49%) of 39 fetuses in group A and in all 5 fetuses (100%) in group B. This difference is significant and leads to a relative risk of 2.05 (95% confidence interval, 1.49-2.83) for neurodevelopmental deficit when predominantly retrograde flow is observed in the fetal aortic isthmus before birth.
This distribution is most likely explained by intraspecific ancestral polymorphism because of the low frequency of the shared haplotype and because the Isthmus of Panama is a strong barrier to pollen flow for this insect-pollinated species [ 25].
